Bonding a polymer member to a metallic member

ABSTRACT

This invention is directed to a method of bonding thermoplastic catheter parts to a metallic member such as hypotubing and the product formed. The polymeric material is hot pressed against the metallic member with sufficient pressure to ensure plastic deformation of the polymeric material. A fluid tight bond is formed which can withstand pressures of up to 650 psi.

BACKGROUND OF THE INVENTION

[0001] This invention generally relates to attachment of high strengthpolymeric members to a metallic member and particularly to theattachment of polymeric tubes to metallic tubes in intravascular devicessuch as catheters for use in percutaneous transluminal coronaryangioplasty (PCTA).

[0002] In a typical PTCA procedure a dilatation balloon catheter isadvanced over a guidewire to a desired location within the patient'scoronary anatomy where the balloon of the dilatation catheter isproperly positioned within the stenosis to be dilated. The balloon isthen inflated to a predetermined size with radiopaque liquid atrelatively high pressures (generally 4-20 atmospheres) to dilate thestenosed region of the diseased artery. One or more inflations may beneeded to effectively dilate the stenosis. The catheter may then bewithdrawn from the stenosis or advanced further into the patient'scoronary anatomy to dilate additional stenoses.

[0003] The inflation pressures used in PTCA procedures have increasedconsiderably due to the utilization of high strength balloon materials.However, such higher pressures also place substantial stress on othercatheter components and particularly the junctions between variouscatheter components. Examples of such components and junctions are theadapter and the junction with the proximal end of a metallic hypotubeand the adapter and the distal end of a metallic hypotube and thepolymeric tubular products which form the distal portion of a rapidexchange type dilatation catheter. Present manufacturing proceduresinvolve the use of adhesives, heat shrinking and the like which limitthe materials which can be used and the combination of materials whichcan be used and which complicate the manufacturing procedure. What hasbeen needed and has heretofore been heretofore been unavailable is anuncomplicated procedure which produces high strength, hermeticallysealed bonds.

SUMMARY OF THE INVENTION

[0004] The present invention is directed to a system for securelybonding a high strength polymer material to a metallic member andparticularly a small diameter tubular polymeric product to a smalldiameter tubular metallic product.

[0005] In accordance with the invention the polymeric member is disposedin contact with the metallic member, the polymer member is hot pressedagainst the metallic member at a temperature above the glass transitiontemperature of the polymeric material but less than the melting pointthereof to effect significant plastic deformation of the polymericmaterial. The result is a high strength bond and a fluid tight sealwhich will no leak even under high pressures.

[0006] One presently preferred embodiment of the invention is directedto the bonding of small diameter tubular polymeric members to smalldiameter tubular metallic members. A portion of the metallic member isinserted into the inner lumen of a polymeric tubular member and a heatshrinkable collar is disposed about the portion of the polymeric tubularmember into which the metallic member is disposed. Heat is applied tothe heat shrinkable collar, and the polymeric tubular member, causingthe collar to shrink and apply sufficient pressure against the polymerictubular member to plastically deform it and thereby bond the polymericmaterial to the surface of the metallic member. The heat shrinkablecollar may be left in place or removed from the polymeric tubular memberafter the bond is formed. A masking layer may be provided between thecollar and the polymeric tubular member to prevent bonding andfacilitate removal of the collar.

[0007] Generally, the polymeric material should be a high strengththermoplastic polymer which is at most semi-crystalline, preferablynon-crystalline, and which is not ethylenically cross-linked. Thepreferred polymeric material is an engineering polymer such aspolyetheretherketone (PEEK), e.g. 581G sold by Victrex. Other polymericmaterials include polyetheramide sold under the trademark ULTEM byGeneral Electric, polyphenylene sulfide and polysulfone. The metallicmember may be stainless steel, such as 304 stainless steel, or asuperelastic or pseudoelastic NiTi alloy. Other metallic materials maybe used such as titanium and alloys thereof. There is no special surfacepreparation needed for the metallic members other than removing surfacecontaminants such as oil, grease and the like.

[0008] One of the advantages of the invention is that the bond is strongenough and the seal is sound enough so the number of parts needed toconstruct an intravascular catheter is reduced considerably. Forexample, in present conventional manufacturing practices for rapidexchange type catheters, such as the LIFESTREAM Dilatation Catheter soldby Advanced Cardiovascular Systems, Inc., up to five parts are needed toattach a proximal hub or adapter to the proximal end of a hypotubeshaft. With the present invention the distal end of the adapter can bebonded directly to the proximal extremity of a hypotube.

[0009] In addition to a significant reduction in the number of parts,there is no adhesive used, so there is no requirements for an adhesivecuring step to form an adhesive bond. The bond of the present inventionbetween the polymeric material and metallic material is strong, durableand provides a fluid tight seal between the joined parts. These andother advantages of the invention will become more apparent from thefollowing detailed description and the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is an elevational view, partially in section, of a rapidexchange type dilatation catheter embodying features of the invention.

[0011]FIG. 2 is a transverse cross-sectional view of the catheter shownin FIG. 1 taken along the lines 2-2.

[0012]FIG. 3 is a transverse cross-sectional view of the catheter shownin FIG. 1 taken along the lines 3-3

[0013]FIG. 4 is a transverse cross-sectional view of the catheter shownin FIG. 1 taken along the lines 4-4.

[0014]FIG. 5 is an enlarged partial elevational view of a polymerictubular member in position to be hot pressed against the metallictubular member to facilitate the bonding therebetween.

[0015]FIG. 6 is a longitudinal cross-sectional view of the members shownin FIG. 5 after the boding procedure.

DETAILED DESCRIPTION OF THE INVENTION

[0016] FIGS. 1-5 illustrate a rapid exchange type balloon dilatationcatheter 10 which has an elongated shaft 11 with a dilatation balloon 12on a distal shaft section 13 of the shaft and an adapter 14 on theproximal end of the proximal shaft section 15. The proximal shaft 15 isformed of a metallic hypotube 16 with a lubricious coating 17. Thedistal shaft section 13 includes a distally extending tubular member 18which has a guidewire receiving inner lumen 20 and which extends throughthe interior of the balloon 12 to the port 21 in the distal end of thecatheter. A guidewire 22 is shown disposed within the lumen 20 andextending out the distal port 21 and the proximal port 23. The inflationlumen 24 is in fluid communication with the interior of dilatationballoon 12 through inflation port 25.

[0017] The distal extremity 26 f the adapter 14 is hot pressed bonded tothe proximal extremity of the proximal shaft section 15 in accordancewith the invention. A high strength polymeric tubular extension 27 ishot press bonded to the distal extremity of the proximal shaft section15 in the same manner as the distal extremity of the adapter is bondedto the proximal extremity of the proximal shaft section. In both casesthe coating 17 is removed from the exterior of the hypotube 16 tofacilitate direct bonding to the metallic surface.

[0018]FIGS. 5 and 6 illustrate a presently preferred method of bondingthe polymeric member, tubular extension 27 to the metallic tubularmember 16. As shown in FIG. 5, the distal end of the metallic tubularmember 16 is inserted into the inner lumen 28 of the tubular extension27. A heat shrinkable tubular collar 29 is disposed about the proximalextremity of the tubular extension 27 and heated to heat shrinktemperatures to press the proximal extremity against the exposed surfaceof the tubular member 16. With the high temperatures and the pressuresapplied, the proximal extremity is plastically deformed and is securelybonded to the metallic surface. The distal extremity of the adapter 14is bonded to the proximal extremity of the proximal shaft section inessentially the same manner.

EXAMPLE

[0019] A stainless steel hypotube with an outer diameter of 0.024 inch(0.6 mm) and inner diameter of 0.016 inch (0.4 mm) was inserted into theinner lumen of a polymeric tubular member form of polyetheretherketone(PEEK). The inner lumen of the polymeric tubular member was about 0.026inch (0.7 mm) and the outer diameter was about 0.035 inch (0.9 mm). Ashort piece of a heat shrinkable tubular FEP with an outer diameter ofabout 0.077 inch (2 mm)and an inner diameter of about 0.055 inch (1.4mm) was disposed about the exterior of the polymeric tubular member. Theassembly was subjected to an air stream at 450° F.(232° C.) until thetubing becomes cloudy. Upon cooling, the FEP tubular collar was removed.The bond between the PEEK member and the stainless steel member wassound and leak free at internal pressures of up to 650 psi.

[0020] Although individual features of embodiments of the invention maybe shown in some of the drawings and not in others, those skilled in theart will recognize that individual features of one embodiment of theinvention can be combined with any or all the features of one or more ofthe other embodiments.

What is claimed is:
 1. A method of securing a polymeric member to ametallic member in a high strength fluid tight relationship comprising:a) mounting the polymeric member against the metallic member; and b) hotpressing the polymeric member against the metallic member at atemperature above the glass transition temperature and below the meltingpoint of the polymeric material of the polymeric member while subjectingthe polymeric material to plastic deformation.
 2. The method of claim 1wherein the polymeric member is a tubular element with an inner lumenextending therethrough and at least part of the metallic member isdisposed within the inner lumen of the polymeric member and thepolymeric material surrounding the metallic member is hot pressedagainst the portion of the metallic member within the inner lumen. 3.The method of claim 1 wherein the polymeric material from which thepolymeric member is formed is a thermoplastic polymer selected from thegroup consisting of polyetheretherketone, polyetheramide, polyphenylenesulfide and polysulfone.
 4. The method of claim 1 wherein the hotpressing of the polymeric member against the metallic member includesplacing a heat shrinkable member about the polymeric member and themetallic member, heating the heat shrinkable member to shrink saidmember against the polymeric and metallic members, causing thetemperatures of both the polymeric and metallic members to increase to atemperature above the glass transition temperature of the polymericmaterial and apply adequate pressure to cause the polymeric member to beplastically deform and bond to the metallic member.
 5. The method ofclaim 4 wherein the heat shrinkable member is removed from the junctionbetween the polymeric material and the metallic member.
 6. The method ofclaim 4 wherein the heat shrinkable member is a polymeric collar.
 7. Themethod of claim 4 wherein the polymeric collar is formed of afluoropolymer.
 8. An intravascular catheter with an elongated shaftcomprising: a) an elongated metallic tubular member having proximal anddistal ends and an inner lumen extending between the proximal and distalends; b) a polymeric tubular member having proximal and distal ends andan inner lumen extending between the proximal and distal ends; and c) ahot pressed bond between one part of the metallic tubular member and onepart of the polymeric tubular member.
 9. The intravascular catheter ofclaim 8 wherein the polymeric material is a thermoplastic polymerselected from the group consisting of polyetheretherketone,polyetheramide, polyphenylene sulfide and polysulfone.
 10. Theintravascular catheter of claim 8 wherein the one end of the polymerictubular member is disposed about and hot press bonded to the exterior ofone end of the metallic tubular member.
 11. A balloon dilatationcatheter comprising: a) an elongated proximal shaft section formed atleast in part of a metallic tubular member having proximal and distalends and an inner lumen extending between the proximal and distal ends;b) an elongated distal shaft section formed at least in part of apolymeric tubular member having proximal and distal ends and an innerlumen extending between the proximal and distal ends; c) a hot pressedbond between part of the metallic tubular member and part of thepolymeric tubular member; and d) an inflatable dilatation balloon on thedistal shaft section having an interior in fluid communication with theinner lumen of the polymeric tubular member.
 12. An intravascularcatheter with an elongated shaft comprising: a) an elongated metallictubular member having proximal and distal ends and an inner lumenextending between the proximal and distal ends; b) a polymeric adapterhaving proximal and distal ends and an inner lumen extending between theproximal and distal ends; and c) a hot pressed bond between the proximalend of the metallic tubular member and the distal end of the polymericadapter.
 13. The intravascular catheter of claim 12 wherein the distalend of the polymeric adapter is bonded to the exterior of the proximalend of the metallic tubular member.
 14. The intravascular catheter ofclaim 13 wherein the inner lumen of the metallic tubular member is influid communication with the inner lumen of the adapter.
 15. A rapidexchange type balloon dilatation catheter comprising: a) an elongatedproximal shaft section formed at least in part of a metallic tubularmember having proximal and distal ends and a first inner lumen extendingtherein; b) an elongated distal shaft section, which is formed at leastin part of a polymeric tubular member, having proximal and distal ends,a first port in the distal end and a second port spaced proximal to thedistal end, a dilatation balloon with an interior, a second inner lumenextending therein which is in fluid communication with the first innerlumen in the metallic tubular member and the interior of the dilatationballoon and a third inner lumen which is in fluid communication with thefirst and second ports; and c) a hot pressed bond between part of themetallic tubular member and part of the polymeric tubular member.